#include <atcoder/all>
#include <bits/stdc++.h>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
using namespace atcoder;
using namespace std;

typedef long long ll;

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i];
    bool ok = false;
    rep(i, 0, n) if (a[i] <= 1) ok = true;
    cout << (ok ? "Yes" : "No") << endl;
}